The present invention relates to a drive for a multi-color rotary sheet printing machine.
More particularly, it relates to a drive for such a printing machine, in which the printing mechanisms are connected with one another through a closed gear train which is connected by at least two elastic power input points with a drive train extending parallel to the gear train, while a torsion spring is arranged in each trunnion of the printing cylinder at its drive side.
Drive units of the above mentioned general type are known in the art. It is known to provide torsion springs in the drive of such printing machine for optimal power branching for the purpose of providing a constant definite tooth flank abutment in the gear train and for filtering out the vibrations which can be caused by toothing error or by error during rotation of shafts or gears. This prevents transfer of the vibrations to the cylinders and drums.
In the German document DD-PS No. 140,225 it has been proposed to arrange the torsion spring in the trunnions of the printing cylinder, wherein the spring constant of one torsion spring is greater than the same of other torsion springs. This solution has a disadvantage in that it is necessary to use several different, individually calculated and non-changeable torsion springs for the drive of one multi-color rotary sheet printing machine. These torsion springs are not adjustable to the printing thickness and their support is expensive.